LXVII is a faithful simulation, of the Hewlett-Packard HP-67 programmable scientific calculator. It has the same stack depth and number of memory registers and program steps as the original. The button layout, numeric display formats and program key-codes are also similar although the display has been expanded to 14 significant digits with a 3 digit exponent.

New features were designed with the intent that they extend existing features in a compatible manner.

New features include:

It is document based, so multiple calculators can be active at the same time.

It is multi-threaded so multiple programs can be running at the same time on as many CPUs as are available on the system.

The document based architecture, along with user defined function keys, allows users to redefine LXVII's functionality so that each document is essentially a new calculator, tailored to the user's specific task.

A paper tape panel like that found on the hp-97 desktop calculator is provided for printing out memory registers, intermediate stack values and program listings.

A pull-out drawer can display the current values of the stack, the last-X register, the program counter, all memory locations and all program steps in memory. All values except the program steps can be edited directly within the drawer interface.

All buttons have an assigned single-keystroke key so that the user can get to all calculator functions without the need of the mouse.

All buttons and button labels have active tooltips specifying the button's functions and it's shortcut.

What is new in this release:

Delete when inputting a number now deletes the digits that have been entered.

Copy/Paste now works for the number in the display. Please note that it will convert the number from the proper floating point format to the display format as appropriate.
What that means is that if you copy a number that is showing the exponent (for example "1.23 -025") what you will paste is 1.23E-25. In the same way, pasting the number "12.33E13" into LXVII will display "1.233 014"
Trying to paste "1.233 014" into LXVII will result in a beep, and no change to the stack. The pasted number will always push the stack up. Copy/Paste to and from the stack and memory register display still works as usual.

The paper tape panel has been greatly enhanced. It now has an automated mode which prints the display and operation that was executed and a trace mode that will print each step in a program as it is executed. There is a preference pane to control how it works, and a help page dedicated to explaining it.

The display routines have been generally cleaned up to do a better job with rounding numbers and handling overflow/underflow situations.

General bug fixes in program execution and some of the calculations in the less common functions, including hour, minute second to decimal hour conversion.